#########################################################################
#									#
# gameoflife.R - an R script to implement Conway's Game of Life	    	#
#								  	#
# The starting matrix is created as a size*size matrix with elements 	#
# picked randomly from [0,1]. If grid is set to TRUE, cells will	#
# be represented by boxes, filled or unfilled for populated or 		#
# retrospectively. If grid is set to FALSE, only populated cells will	#
# be shown.								#
#									#
# Luke Jostins, 13/10/07						#
#									#
#########################################################################


# set initial conditions

size <- 150
grid <- FALSE

# create a random matrix (TODO: change to a more interesting one)
M <- matrix(round(c(runif((size^2)))),nrow=size)

# calculate dimensions, and thus the size of the cells
nrows <- dim(M)[1]
ncols <- dim(M)[2]
squaresize <- 60/max(c(nrows+1,ncols+1))

# create vectors for all movememnts
left = c(2:nrows,1)
right = c(nrows,1:nrows-1)
up = c(2:ncols,1)
down = c(ncols,1:ncols-1)

# run the game until something is typed

k = ""
while (nchar(k) == 0){

	# create the neighbour matrix (shifting toroidally)
	M.neigh <- M[,up] + M[left,] + M[,down] + M[right,] + M[left,up] + M[left,down] + M[right,up] + M[right,down]

	# implement rules
	Mnew = M
	Mnew[(M==1 & M.neigh <= 1) | (M==1 & M.neigh >= 4)] <- 0	# kill if alone or crowded
	Mnew[M==0 & M.neigh==3] <- 1 					# revive if 3 neighbours
	M = Mnew
	
	# find co-ordinates of ones (and zeros if asked for)
	M1s <- which((M==1),arr.ind=TRUE)
	if (grid == TRUE) M0s <- which((M==0),arr.ind=TRUE)

	#plot the ones (#and zeroes)
	plot(NA,xlim=c(0,ncols+1),ylim=c(nrows+1,0),axes=FALSE,xlab="",ylab="")
	points(M1s[,c(2,1)],pch=22,cex=squaresize,bg="black")
	if (grid == TRUE) points(M0s[,c(2,1)],pch=22,cex=squaresize)

	# give a prompt, and store result (ensure not NULL)
	k <- scan(what = "character",nmax = 1,blank.lines.skip=TRUE,quiet=TRUE)
	k <- paste(k,"",sep="")
}